When a building's foundations have sunk into the ground, it is often desirable, if not necessary, to raise these foundations so that the building is returned to a level attitude.
Canadian Patent No. 2,031,041 issued on Apr. 16, 1996 discloses such a device for raising the foundations of a building using piles that are then secured to the foundations to maintain the latter at a level position. More particularly, in this Canadian Patent, an L-shaped lifting assembly 5 is inserted under the foundation of the building and is bolted to the concrete thereof, as seen by the horizontal support 24 located under the foundation's footing 2 and by the bolts 23 that extend through holes 22 of the lifting assembly 5. The lifting assembly 5 also includes a vertical tubular member 19 with a pile 6, as seen in FIG. 2, being slidable vertically longitudinally therethrough.
The pile 6 is made of a series of pile sections, such as items 10 and 11 of FIG. 2 of the Canadian Patent, which are connected together via inserts 15 as the pile is driven gradually into the ground. The pile 6 is driven into the ground via a jaw assembly 7 that includes two pivotal jaws 33 and 35 that are positioned on opposite sides of the pile 6. A pair of hydraulic cylinders 8 and 9 connects the lower lifting assembly 5 to the upper jaw assembly 7.
When the cylinders 8 and 9 are extended, the jaws 34 and 35 are adapted to pivot so as to enable the jaw assembly 7 to slide upwardly over and along the pile 6. When the cylinders 8 and 9 are subsequently retracted, the jaws 34 and 35 are adapted to pivot so as to firmly grasp the pile 6 and drive the same into the soil. Repeated extensions and retractions of the cylinders cause the pile 6 to be gradually driven into the soil. When the lower end 13 of the lowermost pile section of the pile 6 reaches solid ground, further retraction of the cylinders 8 and 9 causes the lifting assembly 5 to raise along with the foundation, as the pile 6 cannot itself further displace downwardly.
When the foundation has been sufficiently raised (e.g. the building is now level), the pile 6 and the tubular member 19 are welded together to retain the foundation in the desired position. The jaw assembly 7 and the cylinders 8 and 9 are then removed.
Generally, pile sections 10 and 11 are gradually added to the pile instead of having a single unitary very long pile 6. This becomes necessary when the operation is done from inside of a building where a ceiling limits the length of the pile 6 and forces the same to be made of a series of initially separate pile sections that are gradually connected together in a successive and longitudinal manner, thereby forming the pile 6.
U.S. Pat. No. 6,193,442-B1 issued on Feb. 27, 2001 to May discloses another device for raising and supporting a building foundation via a lifting assembly that includes a bracket adapted to be secured to the base of the foundation, a pier adapted to be driven into the ground until it reaches a layer bedrock, and a support for the pier, which is secured to the bracket and through which the pier extends. A pair of shafts secures a pier plate and a hydraulic plate to the pier support with the pier plate resting atop the pier. A hydraulic jack is positioned on top of the pier plate. The hydraulic plate being rigidly secured to the shafts, when the hydraulic jack is actuated, it forces the pier plate down, as it is held in fixed position by the hydraulic plate, thereby gradually driving the pier into the ground. The hydraulic jack that drives the pier into the ground is located atop the pier and acts downwardly thereon. A separate jack is used to then lift the foundation.
Other systems are disclosed in U.S. Pat. No. 5,246,311 issued on Sep. 21, 1993 to West et al., U.S. Pat. No. 5,123,209 issued on Jun. 23, 1992 to Nally, U.S. Pat. No. 4,765,777 issued on Aug. 23, 1998 to Gregory, U.S. Pat. No. 4,925,345 issued on May 15, 1990 to McCown, Jr. et al., U.S. Pat. No. 6,416,255-B1 issued on Jul. 9, 2002 to Carlson and U.S. Pat. No. 5,116,355 issued on May 26, 1992 to Freeman, III.
When the pile driving and the foundation raising operations are carried out from inside of a building, the pile must again be made of separate sections, new pile sections being added one by one to the upper end of the pile that is being gradually driven into the ground. Each pile section is fed from the top into the foundation lifting device and, as the overall height of typical lifting assemblies are about three to four feet and as the ceiling is less than eight feet high in a basement, each pile section is about three feet long such that it can be inserted from above into the pile driving mechanism of the lifting device. As each new pile section must be connected to the uppermost pile section of the pile, for instance by welding the pile sections together, the pile driving operation needs to be frequently interrupted thereby becoming time consuming.